Dear all,

I am solving an elasticity problem, in which a uniform load (Ktensor) is applied to nodal points on the FE mesh. I put a brief version of my code for your reference.

As you see below, I need to multiply the load (Ktensor) to nodal coordinates. I tried the following options to define nodal coordinates in my weak from equation, and the results are not the same.

```
fespace Vh(Th, [P2, P2]);
Vh [u1, u2]; //unknowns (displacement fluctuations)
Vh [v1, v2]; //test functions (virtual displacement)
macro epsilon(u1,u2) [dx(u1), dy(u2), dx(u2)+dy(u1)] //EOM // strain vector
func Ktensor = [[1., 0.], [0., 0.], [0., 0.]]; // applied load
// >>> Option 1:
Vh [X,Y] = [x, y];
solve Elastic([u1, u2], [v1, v2]) = int2d(Th)(epsilon(v1,v2)'*C*epsilon(u1,u2)) + int2d(Th)(epsilon(v1,v2)'*C*(Ktensor*[X,Y])) ;
// >>> Option 2:
macro coord [x, y] // EOM
solve Elastic([u1, u2], [v1, v2]) = int2d(Th)(epsilon(v1,v2)'*C*epsilon(u1,u2)) + int2d(Th)(epsilon(v1,v2)'*C*(Ktensor*coord)) ;
```

In the above, C is the elastic matrix of the material, and the only difference in the problem formulation is the way that nodal coordinates are defined. But the results are different.

Can anyone help me understand what is the proper way of defining nodal coordinates in my problem?

Thank you !